In many instances it is important to provide such a closure with means indicating to a user whether the container bears the original seal or has previously been opened. For this purpose it is known, e.g. from German published specification No. 20 24 990, to provide the screw cap of the closure with a telltale ring secured to its rim by frangible webs and designed to engage a radially outwardly projecting peripheral flange of the container neck disposed between its screw threads and the container body. Upon the first unscrewing of the cap, the telltale ring if forcibly detached therefrom since it is retained by the flange. With the cap and its ring generally consisting of plastic material, the ring originally fits loose around the neck and is thereafter thermally deformed to underreach the peripheral flange so as not to be disengageable therefrom by simple mechanical means.
In my first-filed application (Ser. No. 395,085) referred to above, I have disclosed and claimed an improved closure of this general type in which the telltale ring is provided with a set of peripherally spaced-apart lugs with inbent extremeities that are elastically hooked onto the peripheral flange of the container neck upon the initial emplacement of the cap thereon. This eliminates the need for a thermal deformation of the ring since the lug extremities snap into position by virtue of their inherent elasticity. Advantageously, these extremities are designed as barbs including an acute angle with the stems supporting them, these stems being preferably heavier than the barbs so as to resist any effort at bending them away in order to disengage the barbs from the shoulder of the container neck.
Even so, however, the closure may not be entirely safe from tampering since it is conceivable that someone may succeed in deflecting the barbs with the aid of, say, an arcuately bent wire.